In a semiconductor device manufacturing process, there is known a Hot-wired CVD (Chemical Vapor Deposition) method or a Cat (catalyst)—CVD method for forming a film, e.g., a W (tungsten) film or a poly-crystalline Si (silicon) film for solar cell or the like, on a substrate, e.g., a semiconductor wafer (hereinafter, referred to as ‘wafer’), by using active species such as ions or radicals activated by a catalyst.
In such CVD method, a catalyst formed of a refractory metal, e.g., W (tungsten), Ir (iridium), Pt (platinum), Mo (molybdenum), Ru (ruthenium), Pd (palladium), Co (cobalt), Ni (nickel) or the like, is heated to, e.g., about 1000° C. or above. Then, film forming species activated by bringing a processing gas containing H2 (hydrogen) gas, NH3 (ammonia) gas or the like, e.g., SiH4 (silane) gas, into contact with the catalyst are supplied to the wafer. As a result, a poly-crystalline Si film, for example, is formed.
As an example of a specific configuration of the CVD apparatus using such catalyst, there is known, e.g., a configuration in which a mounting table for mounting thereon a wafer and a bellows-shaped or net-shaped wire made of a catalyst metal are provided in a processing chamber. The wire is disposed at an area close to the wafer mounted on the mounting table, e.g. hung from the ceiling wall of the processing chamber, so as to face the wafer.
In this configuration, the wire is heated by power supplied thereto, and a processing gas is supplied to the wafer via the area in which the wire is provided. Herein, the film forming species activated by the catalyst are deactivated after a lapse of time (after moving a distance).
For that reason, the wire is disposed near the mounting table so that the area where the film forming species are activated is positioned close to the wafer mounted on the mounting table.
Meanwhile, in the case of using the wire made of a catalyst metal, the following problems are generated. In other words, the catalyst metal line (wire) is directly heated by power supplied thereto, so that the wire may be disconnected if the catalyst is oxidized by the processing gas, for example. If the wire once is disconnected, it is difficult to reconnect the wire. For example, the wire needs to be replaced as a whole, and this leads to increase of a cost. Further, since the catalyst is disposed close to the wafer on the mounting table, the wire may be bent by heating and may be brought into contact with the wafer.
In order to prevent the catalyst from being short-circuited during the film forming process, the catalyst needs to be electrically insulated from the wafer or the processing chamber. At the same time, the vacuum atmosphere in the processing chamber should be maintained. Thus, the wire needs to be airtightly maintained while being hung inside the processing chamber. In other words, the freedom of installation of the catalyst is decreased, and the effective area of the catalyst is limited. Moreover, since the catalyst material is machined into a wire, fabrication cost increases compared to the case of using a bulk material.
Japanese Patent Publication Application No. 2001-358077 discloses a film forming apparatus using a plate-shaped catalyst. However, it is difficult to uniformly heat the plate while preventing the plate from being broken at a high temperature. It is further difficult to sustain the high-temperature plate while preventing the high-temperature plate from being short-circuited with respect to the wafer or the processing chamber.
Furthermore, when the plate is disposed to face the wafer, it is difficult to uniformly supply a processing gas or active species to the wafer. Although Japanese Patent Application Publications Nos. H9-106883, 2005-238099, H6-31178, H9-32536, H11-67727, H8-250438, and 2006-135349 disclose the prior arts related to the present invention, the aforementioned drawbacks are not considered at all.